Process of granulating calcium cyanamid



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To all whom it may coacem:

Be it known that 1, PAUL Saves, cltlzen of the French Republi residingat Toulouse, Haute-Garonne, France, have 1nvent ed certain new and usefulllmprovements 1n Processes, of Granulating. Calcium Cyanamid, of which the following isa specification. I

This inventiontrelates to a new process of granulating calcium 0 anamid and has for I its object to further t e use of calcium cyanamid as an ammonia-potassic fert lizer.

The new process consists in treating calcium cyanamid by means of water to whlch potassium silicatehas been added.

This operation is edected at the time of extinguishing the cyanamid by means of a hydrator. The resulting paste is then conducted into a kneading machine and passes finally into a hot-air drier similar to that used for desiccating superphosphates. The treatment is finished by a suitable crushing.

Potassium silicate hasvery prominent agglutinating properties and is moreover soluble in water Exposed 'to the air, it transforms gradually into potassium carbonate.

In his treatise of chemistry, 7 Ustwald states, alkalinevsilicatesv are decomposed in thesoil and pass to the state of carbonates. At low temperature carbon dioxid expels silicon dioxid or acid from its combinations.

As a consequence thereof the system car bonate and s1l1con dioxid or acld is more stable than. the inverse: carbon dioxid and silicate. 7'

This matter of fact has been corroborated also by Kuhlmann who has demonstrated that a silicate solution exposed to air attracts carbon dioxid and converts gradually into a jelly of silica, when there is simultaneous formation of alkaline carbonate. In his addition an excess of potash which turns immediately to potassium carbonate.

Let. us now consider the reactions which occur in the soil with cyanamid granulated by means of silicate. first: I V

Then cyan'amid decomposes according to the formula fipeeification of Letters Patent.

Air and water give Patented nee. e, rear, Application filed November 2a 1919; Serial are. 340,079. If

' Part of the transformed silica is dissolved and carried away bywater. The-other part combines with certain soil constituents. Such is the formation. of hydrated magnesium silicate.

The so formed potassium carbonate is very, soluble in water; simulated by. plants and fore a first class. potassic lit isdirectly asconstitutes therefertilizer.

Thus, the products resulting from the de-' compositions of potassium silicate and cyanamid are as follows: ammonia, potassium carbonate,

Granulation of calcium cyanamid by means of potassium'silicate may be done in two' different ways, according. sult aimed at, namel 1 simple granulation; I 2 high dose granulation permitting of calcium carbonate a'ndsilica.

to the reutilizing the product formed as an ammoniapotas'sic fertilizer.

The complete scarcity of potassium sili cate during the war has obliged the inventor to use a product of a quasi abnorma'l composition containing little potash.

Let us now considerthe results secured by these various experiments. 7

Simple granuZati0n.-'The utilized silicate of potassium was of 32.5 B. at-l9 centi-' grader made:

Silicate of potassium 130 grams. Water 40 gr.

titrating 32.5 Be. at 19 o. lowing proportions were taken:

Cyanamid l gr. Silicate of potassium at 32.5

Be .55 gr,

The weight of this mixture the wet state.

.cyanamiol.

Accordln granules of the following contents:

chanically appears in the form of small grams of a gray tint which do not soil nor Nitrogen K 'U soluble in water fi Then the folis iooIgr. in After having been dried, it yields a weight of 60 gr. granulated i to this process, a raw cyanamld containing 15% 1n1t1al nltrogen gives 35 i The following mixture has, been burn the hands of the manipulator. .Tts

' odor has completely disappeared.

This material is nondusty so that manual spreading is easily efleoted. I The-treatment it has been .submitted to, permits of purifying the material and obtaining a product which resists the action of air but decomposes easily within the soil. High dose granuZatin. Now. we pass to the second case, i.e., obtaining a granulated cyanamid which maybe considered as an 1 at 19 C ammonia-potassic fertilizer, suitable for the composition of a complete fertilizer.

' To accomplish this mode of granulation,

the following mixture is made:

100 gr of raw cyanamid containing .15.4Q% of nitrogen.

200 gr. of potassium silicate of 32.5 B.

which makes together 300 gr. .of materials.

"Aijer having dried the paste, water having been eliminated, the total weight is reduced to only 185 gr. Thus a loss occurred amounting to: Y

' 7 300 1852115 gr. i. e, 38.33%.

The resulting product is a mixture of cyanamid and potassium silicate.

The analysis of this cyanamid,'madeeight days after preparation, has given the following results Nitrogen 1 8.27% K 0 soluble in water 4.47%

which makes together 12.74% available to the plants. The slight difference observed in comparison with the primitive cyanamid and which amounts to:

is onlydue to contribution of silica from the silicate and impurities which dilute the" nitrogen in a greater quantity of material.

Consequently this nitrogen is not lost.

The product resultingfrom said treatment -has to a higher degree the same physical properties that are obtained from the preceding one. Moreover, it contains a higher amount of potash.

Obviously, the results obtained by the above stated experiments may be'largely surpassed by making use of a normal potassium silicate. It will be sufiicient to previously know the'compositio'n of the silicate utilized,

- 1n order to bring it back to the degree of fluidity and the potash contents desired. The hardness of cyanamid granules depends exclusively on the viscosity of the silicated solution.

cyanamid containing 15.40% of nitrogen and a layer of granulated cyanamid (nitrogen: 8.27%) all conditions being equal, have been leftto the air for one months duration.

After said time, the raw cyanamid becomes grumous, whereas the appearance of the granulated cyanamid has undergone no change at all.

Nitrogen contents have become as follows:

- As to raw cyanamid: 13.78%, 2'. 6., a loss of 15.40 13.78:1.62% of nitrogen.

As to granulated cyanamid: 8.12%, the nitrogen loss amounting thus to 8.27 --8.12: 0.15%. I

This shows the advantage secured by granulation.

The present process is the more practical as potassium silicate is, in normal times, a cheap material which is produced on a large scale. Moreover, its transformation into potassium carbonate occurring slowly, its mixture with cyanamid is all the more useful as the latter is classed under the slowly acting fertilizers, wherefrom it appears that their actions will show themselves at the same time.

The thus obtained granulated cyanamid may constitute the basis of a complete fertilizer; the only constituent failing 1s phosphoric acid. It will be sufiicient to lncorporate corresponding amounts of bone-ashes titrating 28 to 29% of P 0 or dephosphoration slags containing 18% of P 0 n the form of phosphate of lime and alumina.

Adding superphosphates is to be avoided as they would undergo the phenomenon of retrogradation owing to excess of lime.

This fertilizer would include the'four constituents which are indispensable to agriculture, 11. e.: nitrogen, potash, phosphoric acid and calcium carbonate, the latter being ab solutely necessary to nitrification and to assimilation of potash.

The process of granulation disclosed in the present specification may be applied by means of all,silicates, such as those of sodium, calcium, magnesium, aluminium and (or) manganese.

I claim:

1. The process of granulating calcium cyanamid, consisting in treating calcium cyanamid with a silicate solution, and crushing.

2. The process of granulating calcium eytn amid with a naooeeo anamid, consisting in treating calcium cyanamid with a solution of a silicate in Water, and crushing.

3. The process of granulating calcium cyananiid, consisting in treating calcium cyanamid with a solution of potassium silicate, and crushing. I i

4:. The process of granulating calcium cyanamid, consisting in treating calcium cyanpotassium silicate solution at the time of extinguishing the cvanamid, submitting the resulting mass to a kneading ma chine, drying the resulting mixture and crushing the desiccated material to granulated form. I

lin testimony whereof, I aflix my signature in the presence of two Witnesses.

PAUL savns. Witnesses:

JAMES D. CHILDS, A. N, .RANDALL. 

